#include <stdio.h>
#include <malloc.h>

typedef struct Triple
{
    int i;
    int j;
    int e;
} Triple, *TriplePtr;

typedef struct CompressedMatrix
{
    int rows;
    int columns;
    int numElements;
    Triple *elements;
} CompressedMatrix, *CompressedMatrixPtr;

CompressedMatrixPtr initCompressedMatrix(int paraRows, int paraColumns, int paraElements, int **paraData)
{
    int i;
    CompressedMatrixPtr resultPtr = (CompressedMatrixPtr)malloc(sizeof(struct CompressedMatrix));

    resultPtr->rows = paraRows;
    resultPtr->columns = paraColumns;
    resultPtr->numElements = paraElements;
    resultPtr->elements = (TriplePtr)malloc(paraElements * sizeof(struct Triple));

    for (i = 0; i < paraElements; i++)
    {
        resultPtr->elements[i].i = paraData[i][0];
        resultPtr->elements[i].j = paraData[i][1];
        resultPtr->elements[i].e = paraData[i][2];
    }

    return resultPtr;
}

void printCompressedMatrix(CompressedMatrixPtr paraPtr)
{
    int i;
    for (i = 0; i < paraPtr->numElements; i++)
    {
        printf("(%d, %d):%d\r\n", paraPtr->elements[i].i, paraPtr->elements[i].j, paraPtr->elements[i].e);
    }
}

CompressedMatrixPtr transposeCompressedMatrix(CompressedMatrixPtr paraPtr)
{
    int i, tempcolumn, tempPosition;
    int *tempcolumnCounts = (int *)malloc(paraPtr->columns * sizeof(int));
    int *tempOffsets = (int *)malloc(paraPtr->columns * sizeof(int));
    for (i = 0; i < paraPtr->columns; i++)
    {
        tempcolumnCounts[i] = 0;
    }

    CompressedMatrixPtr resultPtr = (CompressedMatrixPtr)malloc(sizeof(struct CompressedMatrix));
    resultPtr->rows = paraPtr->columns;
    resultPtr->columns = paraPtr->rows;
    resultPtr->numElements = paraPtr->numElements;

    resultPtr->elements = (TriplePtr)malloc(paraPtr->numElements * sizeof(struct Triple));

    for (i = 0; i < paraPtr->numElements; i++)
    {
        tempcolumnCounts[paraPtr->elements[i].j]++;
    }
    tempOffsets[0] = 0;
    for (i = 1; i < paraPtr->columns; i++)
    {
        tempOffsets[i] = tempOffsets[i - 1] + tempcolumnCounts[i - 1];
        printf("tempOffsets[%d]=%d\r\n", i, tempOffsets[i]);
    }

    for (i = 0; i < paraPtr->numElements; i++)
    {
        tempcolumn = paraPtr->elements[i].j;
        tempPosition = tempOffsets[tempcolumn];

        resultPtr->elements[tempPosition].i = paraPtr->elements[i].j;
        resultPtr->elements[tempPosition].j = paraPtr->elements[i].i;
        resultPtr->elements[tempPosition].e = paraPtr->elements[i].e;

        tempOffsets[tempcolumn]++;
    }
    return resultPtr;
}

void test()
{
    CompressedMatrixPtr tempPtr1, tempPtr2;
    int i, j, tempElements;

    tempElements = 4;
    int **tempMatrix1 = (int **)malloc(tempElements * sizeof(int *));
    for (i = 0; i < tempElements; i++)
    {
        tempMatrix1[i] = (int *)malloc(3 * sizeof(int));
    }

    int tempMatrix2[4][3] = {{0, 0, 2}, {0, 2, 3}, {2, 0, 5}, {2, 1, 6}};
    for (i = 0; i < tempElements; i++)
    {
        for (j = 0; j < 3; j++)
        {
            tempMatrix1[i][j] = tempMatrix2[i][j];
        }
    }

    tempPtr1 = initCompressedMatrix(2, 3, 4, tempMatrix1);
    printf("After initialization.\r\n");
    printCompressedMatrix(tempPtr1);

    tempPtr2 = transposeCompressedMatrix(tempPtr1);
    printf("After transpose.\r\n");
    printCompressedMatrix(tempPtr2);
}
int main()
{
    test();
    return 0;
}
